Optimized BaseDatabaseSchemaEditor._effective_default() a bit,
Optimized BaseDatabaseSchemaEditor._effective_default() a bit,

This eliminates an unneeded call to datetime.now() when
field.get_internal_type() equals "DateTimeField".
monetate/django,felixxm/django,solarissmoke/django,ghickman/django,takis/django,apollo13/django,manhhomienbienthuy/django,apollo13/django,felixxm/django,atul-bhouraskar/django,rsalmaso/django,dsanders11/django,solarissmoke/django,django/django,apollo13/django,rsalmaso/django,monetate/django,MarkusH/django,solarissmoke/django,ghickman/django,shaib/django,auvipy/django,atul-bhouraskar/django,blighj/django,dsanders11/django,MarkusH/django,django/django,shaib/django,solarissmoke/django,atul-bhouraskar/django,felixxm/django,blighj/django,takis/django,MarkusH/django,shaib/django,ghickman/django,ghickman/django,auvipy/django,dsanders11/django,django/django,monetate/django,shaib/django,rsalmaso/django,auvipy/django,blighj/django,atul-bhouraskar/django,takis/django,pauloxnet/django,pauloxnet/django,monetate/django,takis/django,manhhomienbienthuy/django,apollo13/django,manhhomienbienthuy/django,pauloxnet/django,rsalmaso/django,django/django,felixxm/django,auvipy/django,blighj/django,manhhomienbienthuy/django,pauloxnet/django,dsanders11/django,MarkusH/django